Method for depositing a material film on a substrate within a reaction chamber by a cyclical deposition process and related device structures

ABSTRACT

A method of depositing a material film on a substrate within a reaction chamber by a cyclical deposition process is disclosed. The method may include: contacting the substrate with a first vapor phase reactant and purging the reaction chamber with a first main purge. The method also includes: contacting the substrate with a second vapor phase reactant by two or more micro pulsing processes, wherein each micro pulsing process comprises: contacting the substrate with a micro pulse of a second vapor phase reactant; and purging the reaction chamber with a micro purge, wherein each of the micro pulses of the second vapor phase reactant provides a substantially constant concentration of the second vapor phase reactant into the reaction chamber. The method may also include; purging the reaction chamber with a second main purge. Device structures including a material film deposited by the methods of the disclosure are also disclosed.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No.62/617,959, entitled “METHOD FOR DEPOSITING A MATERIAL FILM ON ASUBSTRATE WITHIN A REACTION CHAMBER BY A CYCLICAL DEPOSITION PROCESS ANDRELATED DEVICE STRUCTURES” and filed on Jan. 16, 2018, the disclosure ofwhich is hereby incorporated herein for reference.

FIELD OF INVENTION

The present disclosure relates generally to methods for depositing amaterial film on a substrate within a reaction chamber by a cyclicaldeposition process and particularly methods for depositing transitionmetal aluminum carbide films by a cyclical deposition process. Thepresent disclosure is also related generally to device structurescomprising a material film deposited by a cyclical deposition process.

BACKGROUND OF THE DISCLOSURE

Complementary metal-oxide-semiconductor (CMOS) technology hasconventionally utilized n-type and p-type polysilicon as the gateelectrode material. However, doped polysilicon may not be an ideal gateelectrode material for advanced technology node applications. Forexample, although doped polysilicon is conductive, there may still be asurface region which can be depleted of carriers under bias. Thisdepleted region may appear as an extra gate insulator thickness,commonly referred to as gate depletion, and may contribute to theequivalent oxide thickness. While the gate depletion region may be thin,on the order of a few Angstroms, it may become significant as the gateoxide thicknesses are reduced in advanced technology node applications.As a further example, polysilicon does not exhibit an ideal effectivework function (eWF) for both NMOS and PMOS devices. To overcome thenon-ideal effective work function of doped polysilicon, a thresholdvoltage adjustment implantation may be utilized. However, as devicegeometries reduce in advanced technology node applications, thethreshold voltage adjustment implantation processes may becomeincreasingly complex.

To overcome the problems associated with doped polysilicon gateelectrodes, the non-ideal doped polysilicon gate material may bereplaced with alternative materials, such as, for example, metals, metalnitrides and metal carbides. For example, the properties of a metalcarbide may be utilized to provide a more ideal effective work functionfor both NMOS and PMOS devices, wherein the effective work function ofthe transistor gate structure, i.e., the energy need to extract anelectron, may be compatible with the barrier height of the semiconductormaterial. Accordingly, methods are desired for forming gate electrodeswith preferred effective work functions.

In addition, as semiconductor device die area decreases with eachtechnology generation, some circuit designs are using more structureswith high aspect ratio features in order to better use the availablechip area. For example, certain dynamic random access memory (DRAM)capacitors may employ deep trenches. Such trenches can be very narrowand deep, having aspect ratios of 40:1 or greater. Other examples ofdevices including high aspect ratio features may includemicroelectromechanical systems (MEMS) devices in which the surfaces tobe coated often entail reaching through holes to cavities with reentrantprofiles.

When depositing a material film on a surface of a high aspect ratiodevice feature it is often desirable that the material films aredeposited conformally to the underlying topography of the high aspectfeature. As used herein, conformality may refer to substantiallycomplete uniform coverage of a target surface. However, it is notstraightforward to uniformly deposit materials directly over high aspectratio device structures in order to create material films that meetcertain specifications for a desired application. For example, whenutilizing an atomic layer deposition process to deposit a conformalmaterial film over a device structure including high aspect ratiofeatures it may be challenging to supply a vapor phase reactantconsistently, pulse after pulse, with enough vapor concentration toensure conformal, uniform, deposition over the high aspect ratiofeatures, especially in the bottom of deep trench features. Accordingly,methods are desirable for enabling conformal, uniform deposition oversemiconductor device structures and particularly for deposition overhigh aspect ratio device features.

SUMMARY OF THE DISCLOSURE

This summary is provided to introduce a selection of concepts in asimplified form. These concepts are described in further detail in thedetailed description of example embodiments of the disclosure below.This summary is not intended to identify key features or essentialfeatures of the claimed subject matter, nor is it intended to be used tolimit the scope of the claimed subject matter.

In some embodiments, methods of depositing a material film on asubstrate within a reaction chamber by a cyclical deposition process areprovided. The method may comprise: contacting the substrate with a firstvapor phase reactant; and purging the reaction chamber with a first mainpurge. The method may also comprise: contacting the substrate with asecond vapor phase reactant by two or more micro pulsing processes,wherein each micro pulsing process comprises: contacting the substratewith a micro pulse of a second vapor phase reactant; and purging thereaction chamber with a micro purge, wherein each of the micro pulses ofthe second vapor phase reactant provides a substantially constantconcentration of the second vapor phase reactant to the reactionchamber. The method may also comprise; purging the reaction chamber witha second main purge.

For purposes of summarizing the invention and the advantages achievedover the prior art, certain objects and advantages of the invention havebeen described herein above. Of course, it is to be understood that notnecessarily all such objects or advantages may be achieved in accordancewith any particular embodiment of the invention. Thus, for example,those skilled in the art will recognize that the invention may beembodied or carried out in a manner that achieves or optimizes oneadvantage or group of advantages as taught or suggested herein withoutnecessarily achieving other objects or advantages as may be taught orsuggested herein.

All of these embodiments are intended to be within the scope of theinvention herein disclosed. These and other embodiments will becomereadily apparent to those skilled in the art from the following detaileddescription of certain embodiments having reference to the attachedfigures, the invention not being limited to any particular embodiment(s)disclosed.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

While the specification concludes with claims particularly pointing outand distinctly claiming what are regarded as embodiments of theinvention, the advantages of embodiments of the disclosure may be morereadily ascertained from the description of certain examples of theembodiments of the disclosure when read in conjunction with theaccompanying drawings, in which:

FIG. 1A illustrates a non-limiting exemplary overall process flow,demonstrating a cyclical deposition process according to the embodimentsof the disclosure;

FIG. 1B illustrates a non-limiting exemplary sub-process of a cyclicaldeposition process, the exemplary sub-process comprising a micro pulsingprocess for providing a vapor phase reactant to a substrate according tothe embodiments of the disclosure;

FIG. 2 illustrates a cross sectional schematic diagram of a devicestructure comprising a material film deposited according to theembodiments of the disclosure;

FIG. 3 illustrates a schematic diagram of a reaction system configuredto perform the methods of the disclosure.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Although certain embodiments and examples are disclosed below, it willbe understood by those in the art that the invention extends beyond thespecifically disclosed embodiments and/or uses of the invention andobvious modifications and equivalents thereof. Thus, it is intended thatthe scope of the invention disclosed should not be limited by theparticular disclosed embodiments described below.

The illustrations presented herein are not meant to be actual views ofany particular material, structure, or device, but are merely idealizedrepresentations that are used to describe embodiments of the disclosure.

As used herein, the term “cyclic deposition” may refer to the sequentialintroduction of precursors (reactants) into a reaction chamber todeposit a film over a substrate and includes deposition techniques suchas atomic layer deposition and cyclical chemical vapor deposition.

As used herein, the term “cyclical chemical vapor deposition” may referto any process wherein a substrate is sequentially exposed to two ormore volatile precursors, which react and/or decompose on a substrate toproduce a desired deposition.

As used herein, the term “substrate” may refer to any underlyingmaterial or materials that may be used, or upon which, a device, acircuit, or a film may be formed.

As used herein, the term “atomic layer deposition” (ALD) may refer to avapor deposition process in which deposition cycles, preferably aplurality of consecutive deposition cycles, are conducted in a reactionchamber. Typically, during each cycle the precursor is chemisorbed to adeposition surface (e.g., a substrate surface or a previously depositedunderlying surface such as material from a previous ALD cycle), forminga monolayer or sub-monolayer that does not readily react with additionalprecursor (i.e., a self-limiting reaction). Thereafter, if necessary, areactant (e.g., another precursor or reaction gas) may subsequently beintroduced into the process chamber for use in converting thechemisorbed precursor to the desired material on the deposition surface.Typically, this reactant is capable of further reaction with theprecursor. Further, purging steps may also be utilized during each cycleto remove excess precursor from the process chamber and/or remove excessreactant and/or reaction byproducts from the process chamber afterconversion of the chemisorbed precursor. Further, the term “atomic layerdeposition,” as used herein, is also meant to include processesdesignated by related terms such as, “chemical vapor atomic layerdeposition”, “atomic layer epitaxy” (ALE), molecular beam epitaxy (MBE),gas source MBE, or organometallic MBE, and chemical beam epitaxy whenperformed with alternating pulses of precursor composition(s), reactivegas, and purge (e.g., inert carrier) gas.

As used herein, the term “film” and “thin film” may refer to anycontinuous or non-continuous structures and material deposited by themethods disclosed herein. For example, “film” and “thin film” couldinclude 2D materials, nanorods, nanotubes, or nanoparticles or evenpartial or full molecular layers or partial or full atomic layers orclusters of atoms and/or molecules. “Film” and “thin film” may comprisematerial or a layer with pinholes, but still be at least partiallycontinuous.

As used herein, the term “work function metal” may refer to anyconductive metal-containing material that results in an appropriateeffective work function when formed in, on or over the gate dielectricof a semiconductor device.

As used herein, the term “metalorganic” or “organometallic” are usedinterchangeably and may refer to organic compounds containing a metalspecies.

Organometallic compounds may be considered to be subclass ofmetalorganic compounds having direct metal-carbon bonds.

A number of example materials are given throughout the embodiments ofthe current disclosure, it should be noted that the chemical formulasgiven for each of the example materials should not be construed aslimiting and that the non-limiting example materials given should not belimited by a given example stoichiometry.

The present disclosure includes methods and device structures that maybe used to form transistor gate structures comprising one or more workfunction metals, wherein the work function metals may be formedutilizing cyclical deposition processes, such as, for example, atomiclayer deposition processes. The existing work function metals that maybe utilized in the ALD formation of gate electrodes may have limitationsdue to their unsuitable effective work function values. For example, itis known that the effective work function of a material may vary as afunction of its thickness. Therefore, as device geometries decrease inadvance technology node applications, the thickness of the correspondingdevice films, such as the work function metal(s) of the gate electrode,may also decrease with an associated change in the value of effectivework function. Such a change in the effective work function of the gateelectrode may result in a non-ideal effective work function for bothNMOS and PMOS device structures. Methods and structures are thereforerequired to provide a more desirable gate electrode. Examples of suchmethods and structures are disclosed in further detail herein.

In addition, the present disclosure also includes methods for depositinga conformal, uniform material film over a substrate, and particularlyover a device structure including high aspect ratio features. Forexample, in a cyclical deposition process, it may be necessary toincrease the dose of one of more of the vapor phase reactants involvedin the deposition process to ensure that sufficient reactant contactsthe entirety of the surface of the substrate. Attempts to increase thedosage of the vapor phase reactants in a cyclical deposition process mayinvolve either increasing the pulse time or simply repeated pulsingmultiple times. However, one problem with increasing the pulse time invapor deposition apparatus, such as ALD or CVD reactors, is that a mereincrease in the pulse time does not compensate for the increased surfacearea of the substrate, as the precursor concentration typically dropsquickly with increased or longer pulse times. A mere increase in pulsetime typically results in diminished concentration of the vapor phasereactant. Similarly, simply pulsing the same source chemical multipletimes consecutively also leads to diminished precursor concentration ineach subsequent pulse. Accordingly, the embodiments of the disclosuremay include methods that utilize a micro pulsing process comprising twoor more sequential micro pulses of vapor phase reactant and a micropurge of the substrate. In the micro pulsing process, the concentrationof the vapor phase reactant provided into the reaction chamber, andcontacting the substrate, may be substantially constant from pulse topulse thereby supplying a uniform concentration of a vapor phasereactant to the substrate and allowing conformal, uniform deposition ofmaterial films. The micro pulsing process of the current disclosure maytherefore provide a uniform, high dose of vapor phase reactant pulses toa reaction chamber, and the substrate within.

Therefore, the embodiments of the disclosure may comprise methods fordepositing a material film on a substrate within a reaction chamber by acyclical deposition process. In some embodiments, the methods maycomprise: contacting the substrate with a first vapor phase reactant andpurging the reaction chamber with a first main purge. The methods of thedisclosure may also comprise: contacting the substrate with a secondvapor phase reactant by two or more micro pulsing processes, whereineach micro pulsing process comprises: contacting the substrate with amicro pulse of a second vapor phase reactant; and purging the reactionchamber with a micro purge; wherein each of the micro pulses of thesecond vapor phase reactant provides a substantially constantconcentration of the second vapor phase reactant into the reactionchamber. In some embodiments, the methods of the disclosure may alsocomprise, purging the reaction chamber with a second main purge.

A non-limiting example embodiment of a cyclical deposition process mayinclude atomic layer deposition (ALD), wherein ALD is based on typicallyself-limiting reactions, whereby sequential and alternating pulses ofreactants are used to deposit about one atomic (or molecular) monolayerof material per deposition cycle. The deposition conditions andprecursors are typically selected to provide self-saturating reactions,such that an absorbed layer of one reactant leaves a surface terminationthat is non-reactive with the gas phase reactants of the same reactants.The substrate is subsequently contacted with a different reactant thatreacts with the previous termination to enable continued deposition.Thus, each cycle of alternated pulses typically leaves no more thanabout one monolayer of the desired material. However, as mentionedabove, the skilled artisan will recognize that in one or more ALD cyclesmore than one monolayer of material may be deposited, for example, ifsome gas phase reactions occur despite the alternating nature of theprocess.

In an ALD-type process for depositing a material film, such as, forexample, a transition metal aluminum carbide film, one deposition cyclemay comprise exposing the substrate to a first reactant, removing anyunreacted first reactant and reaction byproducts from the reactionchamber, and exposing the substrate to a second reactant via two or moremicro pulsing processes, followed by a second removal step. In someembodiments of the disclosure, the first reactant may comprise a metalvapor phase reactant (“the metal precursor”) and the second reactant maycomprise a carbon vapor phase reactant (“the carbon precursor”).

Precursors may be separated by inert gases, such as argon (Ar) ornitrogen (N2), to prevent gas-phase reactions between reactants andenable self-saturating surface reactions. In some embodiments, however,the substrate may be moved to separately contact a first vapor phasereactant and a second vapor phase reactant. Because the reactionsself-saturate, strict temperature control of the substrates and precisedosage control of the precursors may not be required. However, thesubstrate temperature is preferably such that an incident gas speciesdoes not condense into monolayers nor decompose on the surface. Surpluschemicals and reaction byproducts, if any, are removed from thesubstrate surface, such as by purging the reaction space or by movingthe substrate, before the substrate is contacted with the next reactivechemical. Undesired gaseous molecules can be effectively expelled from areaction space with the help of an inert purging gas. A vacuum pump maybe used to assist in the purging.

Reactors capable of being used to deposit material films, such as, forexample, transition metal aluminum carbides, can be used for thedeposition processes described herein. Such reactors include ALDreactors, as well as CVD reactors, configured to provide the precursors.According to some embodiments, a showerhead reactor may be used.According to some embodiments, cross-flow, batch, minibatch, or spatialALD reactors may be used.

The deposition processes described herein may optionally be carried outin a reactor or reaction chamber connected to a cluster tool. In acluster tool, because each reaction chamber is dedicated to one type ofprocess, the temperature of the reaction chamber in each module can bekept constant, which improves the throughput compared to a reactor inwhich the substrate is heated up to the process temperature before eachrun. Additionally, in a cluster tool it is possible to reduce the timeto pump the reaction chamber to the desired process pressure levelsbetween substrates. In some embodiments of the disclosure, thedeposition process may be performed in a cluster tool comprisingmultiple reaction chambers, wherein each individual reaction chamber maybe utilized to expose the substrate to an individual precursor gas andthe substrate may be transferred between different reaction chambers forexposure to multiple precursors gases, the transfer of the substratebeing performed under a controlled ambient to preventoxidation/contamination of the substrate. In some embodiments of thedisclosure, the deposition process may be performed in a cluster toolcomprising multiple reaction chambers, wherein each individual reactionchamber may be configured to heat the substrate to a differentdeposition temperature.

A stand-alone reactor may be equipped with a load-lock. In that case, itis not necessary to cool down the reaction chamber between each run. Insome embodiments, a deposition process for depositing a material film,such as a metal containing film, may comprise a plurality of depositioncycles, for example ALD cycles or cyclical CVD cycles.

In some embodiments, a cyclical deposition process may be used to form amaterial film on a substrate and the cyclical deposition process may bean ALD type process. In some embodiments, the cyclical depositionprocess may be a hybrid ALD/CVD or a cyclical CVD process. For example,in some embodiments, the growth rate of the ALD process may be lowcompared with a CVD process. One approach to increase the growth ratemay be that of operating at a higher substrate temperature than thattypically employed in an ALD process, resulting in a chemical vapordeposition process, but still taking advantage of the sequentialintroduction of precursors, such a process may be referred to ascyclical CVD.

According to some embodiments of the disclosure, ALD processes may beused to form a material film, such as, for example, a transition metalaluminum carbide, on a substrate, such as an integrated circuit workpiece. In some embodiments, of the disclosure, each ALD cycle maycomprise two distinct deposition steps or phases. In a first phase ofthe deposition cycle (“the metal phase”), the substrate surface on whichdeposition is desired may be contacted with a first vapor phase reactantcomprising a metal precursor which chemisorbs on to the surface of thesubstrate, forming no more than about one monolayer of reactant specieson the surface of the substrate. In a second phase of the deposition(“the carbon phase”), the substrate surface on which deposition isdesired may be contacted with two or more micro pulses of a second vaporphase reactant comprising at least a carbon containing vapor phasereactant, i.e., the carbon precursor, wherein the material film may bedeposited due to the reaction between the metal vapor phase reactant andthe carbon vapor phase reactant.

In some embodiments of disclosure, a cyclical deposition process may beutilized to deposit a material film, such as, for example, a transitionmetal aluminum carbide film, and a non-limiting example of such acyclical deposition process may be understood with reference to FIGS. 1Aand 1B, wherein FIG. 1A illustrates the overall exemplary cyclicaldeposition process and FIG. 1B illustrates a sub-process of the overallprocess, the sub-process comprising a micropulsing process for providinga second vapor phase reactant to the substrate.

In more detail, FIG. 1A illustrates an exemplary overall cyclicaldeposition process 100 including a process block 110, which comprises,providing a substrate into a reaction chamber and heating the substrateto a desired deposition temperature. The reaction chamber utilized forthe deposition may be an atomic layer deposition reaction chamber, or achemical vapor deposition reaction chamber, or any of the reactionchambers as previously described herein. In some embodiments of thedisclosure, the substrate may be heated to a desired depositiontemperature during the cyclical deposition process. For example, thesubstrate may be heated to a substrate temperature of less thanapproximately 750° C., or less than approximately 650° C., or less thanapproximately 550° C., or less than approximately 450° C., or less thanapproximately 350° C., or less than approximately 250° C., or even lessthan approximately 150° C. In some embodiments of the disclosure, thesubstrate temperature during the cyclical deposition process may bebetween 300° C. and 750° C., or between 400° C. and 600° C., or between400° C. and 450° C.

Upon heating the substrate to a desired deposition temperature, theexemplary cyclical deposition process 100 may continue with a processblock 120, which comprises contacting the substrate with a first vaporphase reactant and particularly, in some embodiments, contacting thesubstrate with a first vapor phase reactant comprising one or more metalvapor phase reactants, i.e., the metal precursor. In some embodiments ofthe disclosure, the one or more metal vapor phase reactants may comprisea transition metal component. For example, the transition metalprecursor may comprise at least one of the transition metals selectedfrom the group consisting of, titanium (Ti), zirconium (Zr), hafnium(Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr),molybdenum (Mo), and tungsten (W).

In some embodiments of the disclosure, the metal vapor phase reactantmay comprise a metal halide, such as, for example, one or more of ametal chloride, a metal iodide, a metal fluoride, or a metal bromide. Insome embodiments, the metal vapor phase reactant may comprise atransition metal halide, such as, for example, one or more of atransition metal chloride, a transition metal iodide, a transition metalfluoride, or a transition metal bromide. As a non-limiting exampleembodiment, the first metal vapor phase reactant may comprise a titaniumhalide, such as, for example, titanium tetrachloride (TiCl₄).

In some embodiments of the disclosure, contacting the substrate with afirst vapor phase reactant comprising a metal precursor may compriseexposing the substrate to the metal precursor for a time period ofbetween about 0.01 seconds and about 60 seconds, between about 0.05seconds and about 10 seconds, or between about 0.1 seconds and about 5.0seconds. In addition, during the pulsing of the metal containingprecursor, the flow rate of the metal precursor may be less than 2000sccm, or less than 500 sccm, or even less than 100 sccm. In addition,during the pulsing of the metal precursor over the substrate the flowrate of the metal precursor may range from about 1 to 2000 sccm, fromabout 5 to 1000 sccm, or from about 10 to about 500 sccm.

The exemplary cyclic deposition process 100 of FIG. 1A may continue witha process block 130 comprising, purging the reaction chamber with afirst main purge. For example, excess first vapor phase reactant andreaction byproducts (if any) may be removed from the surface of thesubstrate, e.g., by pumping with an inert gas. In some embodiments ofthe disclosure, the first main purge process may comprise a purge cyclewherein the substrate surface is purged for a time period of less thanapproximately 5.0 seconds, or less than approximately 3.0 seconds, oreven less than approximately 2.0 seconds. Excess first vapor phasereactant, such as, for example, excess metal precursors and any possiblereaction byproducts may be removed with the aid of a vacuum, generatedby a pumping system in fluid communication with the reaction chamber.

Upon purging the reaction chamber with the first main purge, i.e., theprocess block 130 of FIG. 1A, the exemplary cyclical deposition process100 may continue with a process block 140 comprising, contacting thesubstrate with a second vapor phase reactant and particularly, in someembodiments of the disclosure, contacting the substrate with a carbonprecursor by two or more micro pulsing processes.

In more detail, FIG. 1B illustrates the process block 140 as thesub-process 140′ and details the particular embodiments of the micropulsing process for contacting the substrate with two or more micropulses of the second vapor phase reactant, i.e., the carbon precursor.The sub-process 140′ may proceed with process block 142 comprising,contacting the substrate with a micro pulse of the second vapor phasereactant and in particular, in certain embodiments of the disclosure,contacting the substrate with a micro pulse of a carbon precursor.

In some embodiments of the disclosure, the second vapor phase reactantmay comprise one or more carbon vapor phase reactants, i.e., the carbonprecursor. In some embodiments, the one or more carbon vapor phasereactants may comprise one or more metalorganic precursors and the metalcomponent of the metalorganic precursor may also be incorporated intothe material film as it is deposited. In some embodiments of thedisclosure, the one or more carbon precursors may comprise at least onemetalorganic precursor, wherein the metalorganic precursors comprises analuminum (Al) component, i.e., the aluminum metalorganic precursor. Forexample, the aluminum metalorganic precursor may comprise at least oneof trimethylaluminum (TMA), triethylaluminum (TEA),dimethylaluminumhydride (DMAH), or tritertbutylaluminum (TTBA). As anon-limiting example, the first vapor phase reactant may comprisetitanium tetrachloride (TiCl4) and the second vapor phase reactant maycomprise triethylaluminum (TEA), and the material film deposited by theexemplary cyclical deposition process may comprise a titanium aluminumcarbide (TiAlC), wherein the TiCl₄ provides the titanium (Ti) to thematerial film and the TEA provides both the aluminum (Al) and carbon (C)to the material film.

In some embodiments of the disclosure, the second vapor phase reactantmay be supplied to the reaction chamber from a source vessel, i.e., asource vessel containing the second reactant. In some embodiments, thesource vessel may contain the second reactant as a solid source, aliquid source, or a gaseous source. In some embodiments, the secondreactant may comprise a solid dissolved in a suitable solvent in orderto provide a liquid source of the second reactant. In some embodimentsof the disclosure, the source vessel and any intervening gas deliverylines between the source vessel and the reaction chamber may be heatedto a desired temperature to increase the vapor pressure of the reactantand prevent adsorption and condensation of the precursor, thereforeenabling a satisfactory flow of the vapor phase reactant from the sourcevessel to the reaction chamber. In some embodiments of the disclosure,the second vapor phase reactant, e.g., the carbon precursor, maycomprise a low vapor pressure reactant. For example, the second reactantmay comprise a low vapor pressure reactant which has a vapor pressure ofless than 1 Torr at room temperature, or less than 0.1 Torr at roomtemperature, or even less than 0.01 Torr at room temperature.

In some embodiments of the disclosure, contacting the substrate with amicro pulse of the second vapor phase reactant, e.g., a carbonprecursor, may comprise micro pulsing, i.e., contacting, the substrateto the carbon precursor for a time period of between about 0.01 secondsand about 60 seconds, between about 0.05 seconds and about 10 seconds,or between about 0.1 seconds and about 5.0 seconds. In some embodimentof the disclosure, contacting the substrate with a micro pulse of thesecond vapor phase reactant, e.g., a carbon precursor, may comprisemicro pulsing, i.e., contacting, the substrate to the carbon precursorfor a time period of less than approximately 2 seconds, or less thanapproximately 1 second, or less than approximately 0.5 seconds, or evenless than approximately 0.1 seconds.

Upon contacting the substrate with a micro pulse of the second vaporphase reactant, the sub-process 140′ of FIG. 1B may proceed with aprocess block 144 comprising, purging the reaction chamber with a micropurge. For example, excess second vapor phase reactant and reactionbyproducts (if any) may be removed from the surface of the substrate,e.g., by pumping with an inert gas. In some embodiments of thedisclosure, the purge process may comprise a micro purge wherein thesubstrate surface is purged for a time period of between approximately0.1 seconds and approximately 10 seconds, or between approximately 0.5seconds and approximately 3 seconds, or even between approximately 1second and 2 seconds. In some embodiments of the disclosure, the micropurging process may purge the surface of the substrate for a time periodof less than 1 second, or less than 0.5 seconds, or less than 0.2seconds, or even less than 0.1 seconds. Excess second vapor phasereactant, such as, for example, excess carbon precursor and any possiblereaction byproducts may be removed with the aid of a vacuum, generatedby a pumping system in fluid communication with the reaction chamber.

During the micro purging process, i.e., simultaneously to performing themicro purging process of the process block 144, the sub-process 140′ mayalso comprise, replenishing the concentration of the second vapor sourceat the source vessel. In more detail, as the sub-process 140′ contactsthe substrate with a micro pulse of the second vapor phase precursors, acertain concentration of the second vapor phase precursor may bedepleted from the source vessel and/or the gas delivery lines disposedbetween the source vessel and the reaction chamber. If repeated micropulses of the second vapor phase precursor are supplied to the reactionchamber without an intervening micro purging process, then the precursorconcentration entering the reaction chamber (and subsequently contactingthe substrate within the reaction chamber) may decrease over time andthe decrease in concentration of the precursor in each micro pulse mayresult in unsatisfactory deposition characteristics, such as, forexample, non-uniform thickness of the deposited material film.

Upon purging the reaction chamber with a micro purge, i.e., the processblock 144, the micro pulsing process may be repeated at least once, ormay be repeated multiple times. For example, the sub-process 140′ maycomprise a sub-cycle including, contacting the substrate with a micropulse of a second vapor phase reactant (process block 142), and purgingthe reaction chamber with a micro purge (process block 144), wherein thesub-cycle may be repeated at least once, or may be repeated multipletimes. In particular embodiments of the disclosure, having repeated themicro pulsing process at least once, the sub-process 140′ may continuewith a decision gate 146 which determines if the sub-process 140′ iscontinued for a further sub-cycle or if the sub-process 140′ exits at aprocess block 148 and returns to the cyclical deposition process 100 ofFIG. 1A. The decision gate 146 may be determined based upon the desireddose of the second vapor phase reactant to be provided to the reactionchamber and particular provided to a substrate within the reactionchamber. In some embodiments of the disclosure, the sub-cycle ofsub-process 140′ may be repeated two (2) or more times, three (3) ofmore times, five (5) or more times, or even ten (10) or more times. Asthe number of sub-cycles of sub-process 140′ is increased, the dose ofthe second vapor phase reactant provided to the reaction chamber mayaccordingly increase until a desired dose of the second vapor phasereactant is provided into the reaction chamber.

In some embodiments of the disclosure, each sub-cycle, of sub-process140′, comprises contacting the substrate with a micro pulse of thesecond vapor phase reactant, wherein each of the micro pulses of thesecond vapor phase reactant provides a substantially constantconcentration of the second vapor phase reactant into the reactionchamber. Therefore, as opposed to known cyclical deposition methods, themethods of the current disclosure may provide multiple micro pulses of avapor phase reactant to a reaction chamber without a decrease in theconcentration of the vapor phase reactant between each individual micropulses. Each micro pulse provides a substantially constant concentrationof vapor phase reactant to the reaction chamber and as the number ofmicro pulses increases the desired dose of reactant contacting thesubstrate may be increased until a desired dose is reached and thesub-process 140′ exits back into the cyclical deposition process 100 ofFIG. 1A.

After completing the sub-process 140′, the exemplary cyclical depositioncycle 100 may continue with a process block 150 (FIG. 1A) whichcomprises, purging the reaction chamber with a second main purge. Forexample, excess second vapor phase reactant and reaction byproducts (ifany) may be removed from the surface of the substrate, e.g., by pumpingwith an inert gas. In some embodiments of the disclosure, the secondmain purge process may comprise a purge cycle wherein the substratesurface is purged for a time period of less than approximately 5.0seconds, or less than approximately 3.0 seconds, or even less thanapproximately 2.0 seconds. Excess second vapor phase reactant, such as,for example, excess carbon precursor(s) and any possible reactionbyproducts may be removed with the aid of a vacuum, generated by apumping system in fluid communication with the reaction chamber.

Upon completion of the second main purge process, i.e., process block150, the exemplary cyclical deposition process 100 may continue with adecision gate 160, wherein the decision gate 160 is dependent on thethickness of the material film deposited. For example, if the materialfilm is deposited at an insufficient thickness for the desired deviceapplication, the cyclical deposition process may be repeated byreturning to the process block 120 and continuing through a furtherdeposition cycle, wherein one deposition cycle comprises, contacting thesubstrate with a metal precursor (process block 120), purging thereaction chamber with a first main purge (process block 130), contactingthe substrate with a carbon precursor by two or more micro pulsingprocesses (process block 140), and purging the reaction chamber with asecond main purge (process block 150). A deposition cycle, of cyclicaldeposition process 100, may be repeated one or more times until adesired thickness of the material film is deposited over the substrate,upon which the cyclical deposition process 100 may exit at a processblock 170 and the substrate may be subjected to further fabricationprocesses to complete the device structures.

It should be appreciated that in some embodiments of the disclosure, theorder of contacting of the substrate with the first vapor phase reactantand the second vapor phase reactant may be such that the substrate isfirst contacted with the second vapor phase reactant followed by thefirst vapor phase reactant. In addition, in some embodiments, thecyclical deposition process may comprise, contacting the substrate withthe first vapor phase reactant one or more times prior to contacting thesubstrate with the second vapor phase reactant two or more times. Inaddition, in some embodiments of the disclosure, the micro pulsingprocess may be utilized for contacting the substrate with the firstvapor phase reactant, in addition to, or as an alternative to micropulsing the second vapor phase reactant.

In addition, some embodiments of the disclosure may comprise non-plasmareactants, e.g., the first and second vapor phase reactants may besubstantially free of ionized reactive species. In some embodiments, thefirst and second vapor phase reactants are substantially free of ionizedreactive species, excited species, or radical species. For example, boththe first vapor phase reactant and the second vapor phase reactant maycomprise non-plasma reactants to prevent ionization damage of theunderlying substrate and the associated defect thereby created.

In some embodiments of the disclosure, the growth rate of the materialfilm, e.g., a transition metal aluminum carbide, may be from about 0.005Å/cycle to about 5 Å/cycle, from about 0.01 Å/cycle to about 2.0Å/cycle. In some embodiments, the growth rate of the material film maybe from about 0.1 Å/cycle to about 10 Å/cycle. In some embodiments thegrowth rate of the material film is more than about 0.05 Å/cycle, morethan about 0.1 Å/cycle, more than about 0.15 Å/cycle, more than about0.20 Å/cycle, more than about 0.25 Å/cycle or more than about 0.3Å/cycle. In some embodiments the growth rate of the material film isless than about 2.0 Å/cycle, less than about 1.0 Å/cycle, less thanabout 0.75 Å/cycle, less than about 0.5 Å/cycle, or less than about 0.2Å/cycle. In some embodiments of the disclosure, the material filmcomprises a transition metal aluminium carbide deposited with a growthrate of approximately 5 Å/cycle.

Material films deposited by the cyclical deposition processes disclosedherein, such as, for example, a transition metal aluminum carbide, maybe continuous films. In some embodiments, the material film, e.g., atransition metal aluminum carbide, may be continuous at a thicknessbelow approximately 100 nanometers, or below approximately 60nanometers, or below approximately 50 nanometers, or below approximately40 nanometers, or below approximately 30 nanometers, or belowapproximately 20 nanometers, or below approximately 10 nanometers, oreven below approximately 5 nanometers. The continuity referred to hereincan be physical continuity or electrical continuity. In some embodimentsof the disclosure the thickness at which a material film may bephysically continuous may not be the same as the thickness at which afilm is electrically continuous, and vice versa.

In some embodiments of the disclosure, the material film depositedaccording to the cyclical deposition processes described herein, e.g., atransition metal aluminum carbide, may have a thickness from about 20nanometers to about 100 nanometers, or about 20 nanometers to about 60nanometers. In some embodiments, a material film deposited according tosome of the embodiments described herein may have a thickness greaterthan about 20 nanometers, or greater than about 30 nanometers, orgreater than about 40 nanometers, or greater than about 50 nanometers,or greater than about 60 nanometers, or greater than about 100nanometers, or greater than about 250 nanometers, or greater than about500 nanometers, or greater. In some embodiments a material film, e.g., atransition metal aluminum carbide, deposited according to some of theembodiments described herein may have a thickness of less than about 50nanometers, or less than about 30 nanometers, or less than about 20nanometers, or less than about 15 nanometers, or less than about 10nanometers, or less than about 5 nanometers, or less than about 3nanometers, or less than about 2 nanometers, or even less than about 1nanometer.

The cyclical deposition methods described herein, i.e., utilizing two ormicro pulsing processes, may enable the deposition of material films,e.g., transition metal aluminum carbide films, with reduced thicknessnon-uniformities. For example, the material may comprise a titaniumaluminum carbide (TiAlC) film deposited with a thickness non-uniformityhaving a standard deviation of less than 2% one-sigma, or less than 1.5%one-sigma, or less than 1% one-sigma, or even less than 0.5% one-sigma.It should be noted that the thickness non-uniformities described hereinmay include a 3 millimeter edge exclusion.

In some embodiments of the disclosure, the material film may bedeposited on a substrate comprising high aspect ratio features, e.g., athree-dimensional, non-planar substrate. In some embodiments, the stepcoverage of the material film, e.g., a transition metal aluminumcarbide, may be equal to or greater than about 50%, or greater thanabout 80%, or greater than about 90%, or greater than about 95%, orgreater than about 98%, or about 99% or greater on structures havingaspect ratios (height/width) of greater than 2, or greater than 5, orgreater than 10, or greater than 25, or greater than 50, or even greaterthan 100.

In some embodiments of the disclosure the first vapor phase reactant maycomprise a transition metal reactant and the second vapor phase reactantmay comprise a metalorganic reactant, such as, for example, an aluminumcontaining metalorganic reactant. In such embodiments, the material filmdeposited may comprise a transition metal carbide and in particularembodiments the material film deposited may comprise, a transition metalaluminum carbide. For example, a transition metal aluminum carbide maybe represented by the general formula XAlC, wherein X comprises atransition metal, Al is aluminum, and C is carbon. In some embodiments,the transition metal aluminum carbide may comprise a transition metalselected from the group consisting of, titanium (Ti), zirconium (Zr),hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr),molybdenum (Mo), and tungsten (W). In some embodiments of thedisclosure, the transition metal may comprise titanium and thetransition metal aluminum carbide may comprise titanium aluminum carbide(TiAlC).

In some embodiments of the disclosure, the material film depositedcomprises a transition metal aluminum carbide (XAlC), wherein thetransition metal aluminum carbide (XAlC) contains an aluminum content ofgreater than 10 atomic %, or greater than 20 atomic %, or greater than30 atomic %, or greater than 40 atomic %, or even greater than 50 atomic%. In some embodiments of the disclosure, the material film depositedcomprises a titanium aluminum carbide (TiAlC) film which contains analuminum content of greater than 20 atomic-%, or greater than 30 atomic%, or greater than 35 atomic %, or even greater than 40 atomic %. Inembodiments wherein the material film comprises a titanium aluminumcarbide (TiAlC) film, the TiAlC film may contain a titanium content ofless than 40 atomic %, or less than 20 atomic %, or even less than 10atomic %. In addition, in embodiments wherein the material filmcomprises a titanium aluminum carbide (TiAlC) film, the TiAlC film maycontain a carbon content of greater than 20 atomic %, or greater than 30atomic %, or even greater than 40 atomic %. In some embodiments of thedisclosure the material film may comprise a titanium aluminum carbide(TiAlC) film which may comprise an average titanium (Ti) to aluminumcontent (Ti:Al) of less than 0.3, or less than 0.2, or less than 0.15,or even less than 0.10. In the embodiments outlined herein, the atomicconcentration of an element may be determined utilizing Rutherfordbackscattering (RB S).

In additional embodiments, the material film may comprise a transitionmetal aluminum carbide, e.g., a titanium aluminum (TiAlC) film, whichmay comprise less than about 20 atomic % oxygen, or less than about 10atomic % oxygen, or less than about 5 atomic % oxygen, or even less thanabout 2 atomic % oxygen. In further embodiments, the transition metalaluminum carbide film may comprise, less than about 10 atomic %hydrogen, or less than about 5 atomic % of hydrogen, or less than about2 atomic % of hydrogen, or even less than about 1 atomic % of hydrogen.

The material films, e.g., transition metal aluminum carbide films,deposited by the cyclical deposition processes disclosed herein may beutilized in a variety of applications. As a non-limiting exampleembodiment, the material film may comprise a transition metal aluminumcarbide film utilized as a work function metal in a semiconductortransistor application, such as a planar transistor structure or amultiple gate transistor (e.g., FinFET). In more detail, and withreference to FIG. 2, a semiconductor device structure 200 may comprise asemiconductor body 216 and a gate electrode 210 comprising a transitionmetal aluminum carbide (e.g., TiAlC) disposed over the semiconductorbody 216. In some embodiments, the semiconductor device structure 200may comprise a transistor structure and may also include a source region202, a drain region 204, and a channel region 206 disposed therebetween.A transistor gate structure 208 may comprise an electrode, i.e., a gateelectrode, which may be separated from the channel region 206 by a gatedielectric 212. According to the present disclosure, the gate electrode210 may comprise a transition metal aluminum carbide, such as, forexample, a titanium aluminum carbide (TiAlC), deposited by the cyclicaldeposition methods described herein. As shown in FIG. 2, in someembodiments the transistor gate structure 208 may further comprise oneor more additional conductive layers 214 formed on the gate electrode210. The one or more additional conductive layers 214 may comprise atleast one of a polysilicon, a refractory metal, a further transitionmetal carbide, and a transition metal nitride.

In some embodiments of the disclosure, the gate electrode 210 maycomprise a titanium aluminum carbide (TiAlC) film and the transistorgate structure 208 may have an effective work function of less thanapproximately 4.5 eV, or less than approximately 4.3 eV, or even lessthan approximately 4.1 eV. In some embodiments, the gate electrode 210may comprise a titanium aluminum carbide (TiAlC) film and the transistorgate structure 208 may have an effective work function less thanapproximately 4.3 eV, wherein the titanium aluminum carbide (TiAlC) filmhas a thickness of less than 6 nanometers, or less than 3 nanometers, oreven less than 2 nanometers.

Embodiments of the disclosure may also include a reaction systemconfigured for forming the material films, e.g., transition metalaluminum carbide films, of the present disclosure. In more detail, FIG.3 schematically illustrates a reaction system 300 including a reactionchamber 302 that further includes mechanism for retaining a substrate(not shown) under predetermined pressure, temperature, and ambientconditions, and for selectively exposing the substrate to various gases.A precursor reactant source 304 may be coupled by conduits or otherappropriate means 304A to the reaction chamber 302, and may furthercouple to a manifold, valve control system, mass flow control system, ormechanism to control a gaseous precursor originating from the precursorreactant source 304. A precursor (not shown) supplied by the precursorreactant source 304, the reactant (not shown), may be liquid or solidunder room temperature and standard atmospheric pressure conditions.Such a precursor may be vaporized within a reactant source vacuumvessel, which may be maintained at or above a vaporizing temperaturewithin a precursor source chamber. In such embodiments, the vaporizedprecursor may be transported with a carrier gas (e.g., an inactive orinert gas) and then fed into the reaction chamber 302 through conduit304A. In other embodiments, the precursor may be a vapor under standardconditions. In such embodiments, the precursor does not need to bevaporized and may not require a carrier gas. For example, in oneembodiment the precursor may be stored in a gas cylinder. The reactionsystem 300 may also include additional precursor reactant sources, suchas precursor reactant source 306, which may also be coupled to thereaction chamber by conduits 306A as described above.

A purge gas source 308 may also be coupled to the reaction chamber 302via conduits 308A, and selectively supplies various inert or noble gasesto the reaction chamber 302 to assist with the removal of precursor gasor waste gases from the reaction chamber. The various inert or noblegases that may be supplied may originate from a solid, liquid or storedgaseous form.

The reaction system 300 of FIG. 3 may also comprise a system operationand control mechanism 310 that provides electronic circuitry andmechanical components to selectively operate valves, manifolds, pumpsand other equipment included in the reaction system 300. Such circuitryand components operate to introduce precursors, purge gases from therespective precursor sources 304, 306 and purge gas source 308. Thesystem operation and control mechanism 310 also controls timing of gaspulse sequences, temperature of the substrate and reaction chamber, andpressure of the reaction chamber and various other operations necessaryto provide proper operation of the reaction system 300. The operationand control mechanism 310 can include control software and electricallyor pneumatically controlled valves to control flow of precursors,reactants, and purge gases into and out of the reaction chamber 302. Thecontrol system can include modules such as a software or hardwarecomponent, e.g., a FPGA or ASIC, which performs certain tasks. A modulecan advantageously be configured to reside on the addressable storagemedium of the control system and be configured to execute one or moreprocesses.

Those of skill in the relevant arts appreciate that other configurationsof the present reaction system are possible, including a differentnumber and kind of precursor reactant sources and purge gas sources.Further, such persons will also appreciate that there are manyarrangements of valves, conduits, precursor sources, purge gas sourcesthat may be used to accomplish the goal of selectively feeding gasesinto reaction chamber 302. Further, as a schematic representation of areaction system, many components have been omitted for simplicity ofillustration, and such components may include, for example, variousvalves, manifolds, purifiers, heaters, containers, vents, and/orbypasses.

The example embodiments of the disclosure described above do not limitthe scope of the invention, since these embodiments are merely examplesof the embodiments of the invention, which is defined by the appendedclaims and their legal equivalents. Any equivalent embodiments areintended to be within the scope of this invention. Indeed, variousmodifications of the disclosure, in addition to those shown anddescribed herein, such as alternative useful combination of the elementsdescribed, may become apparent to those skilled in the art from thedescription. Such modifications and embodiments are also intended tofall within the scope of the appended claims.

What is claimed is:
 1. A method of depositing a material film on asubstrate within a reaction chamber by a cyclical deposition process,the method comprising; contacting the substrate with a first vapor phasereactant; purging the reaction chamber with a first main purge;contacting the substrate with a second vapor phase reactant by two ormore micro pulsing processes, wherein each micro pulsing process is asub-cycle that comprises: contacting the substrate with a micro pulse ofa second vapor phase reactant, and purging the reaction chamber with amicro purge, wherein each of the micro pulses of the second vapor phasereactant provides a constant concentration of the second vapor phasereactant into the reaction chamber; and purging the reaction chamberwith a second main purge; wherein the material film deposited on thesubstrate comprises a transition metal aluminum carbide; wherein thetransition metal aluminum carbide comprises titanium aluminum carbide(TiAlC); and wherein the titanium aluminum carbide (TiAlC) has anaverage titanium to aluminum content ratio (Ti:Al) of less than 0.15. 2.The method of claim 1, wherein the cyclical deposition process comprisesan atomic layer deposition process.
 3. The method of claim 1, whereinthe cyclical deposition process comprises a cyclical chemical vapordeposition process.
 4. The method of claim 1, wherein the first vaporphase reactant comprises one or more metal vapor phase reactants.
 5. Themethod of claim 4, wherein the one or more metal vapor phase reactantscomprises at least one transition metal selected from the groupconsisting of titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V),niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), andtungsten (W).
 6. The method of claim 4, wherein the one or metal vaporphase reactants comprises at least one of a transition metal chloride, atransition metal bromide, a transition metal iodide, or a transitionmetal fluoride.
 7. The method of claim 1, wherein the second vapor phasereactant comprises a metalorganic precursor.
 8. The method of claim 7,wherein the metalorganic precursor comprises at least one ofdimethylaluminumhydride (DMAH) or tritertbutylaluminum (TTBA).
 9. Themethod of claim 1, wherein each micro pulse of the second vapor phasereactant has a pulse time period of between 0.05 seconds and 10 seconds.10. The method of claim 1, wherein each micro purge has a purge timeperiod of between 0.1 seconds and 10 seconds.
 11. The method of claim 1,wherein the titanium aluminum carbide (TiAlC) has an aluminum atomic-%greater than 20%.
 12. The method of claim 1, wherein the titaniumaluminum carbide (TiAlC) is deposited with a thickness non-uniformitystandard deviation of less than 2% one-sigma.
 13. The method of claim 1,wherein the titanium aluminum carbide (TiAlC) is deposited over anon-planar substrate with a step coverage greater than 90%.
 14. Themethod of claim 1, further comprising replenishing the concentration ofthe second vapor source at the source vessel to a constant concentrationduring each micro purge.
 15. A device structure including a materialfilm deposited by the method of claim
 1. 16. A reaction systemconfigured to perform the method of claim 1.